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Background: Chinese Americans have increased rates for obesity in the United States. Little is known about obesity indicators and chronic illness, and the relationship between them in Chinese Americans.

Methods: A descriptive and cross-sectional study was designed. Chinese-American adults were recruited from a community health center in New York. Obesity indicators including waist circumference (WC), hip circumference (HC), Body Mass Index (BMI), weight to hip ratio, weight to height ratio, fasting blood glucose (FPG), Glycated hemoglobin (HbA1C) were evaluated. Chronic illnesses were assessed using a researcher developed self-report checklist and verified by medical record review.

Results: Among 162 Chinese American participants, who were recruited, 94 subjects had fewer than three chronic illnesses and 68 subjects had three or more chronic illnesses. The three most common chronic illnesses in this population were diabetes (65.4%), hypertension (46.9%), and eye problem (38.3%). Controlling for all demographic factors, numbers of chronic illnesses remained significant associations with obesity indicators of WC (p=0.006), HC (p=0.020), weight to height ratio (p=0.011), HbA1C (p=0.026). Obesity indicators also had significant associations with individual chronic illness of diabetes, hypertension, heart diseases, eye and food problems.

Conclusion: General Obesity indicator (BMI), central obesity indicators (WC, HC, weight to height ratio) and HbA1c were significantly associated with chronic illnesses in Chinese Americans.
 

Obesity indicators; Chronic illness; Chinese Americans
 

The prevalence of obesity is increasing throughout the world. Obesity is widely recognized as a major public health problem in the United States and has been identified as a major source of unsustainable health costs, and morbidity and mortality related to multiple chronic diseases [1,2]. Asian Americans make up 4% of the U.S. population and are projected to increase to 9.3% of the population by the year of 2050 [3,4]. In general, Asian Americans who were born in the United States tend to be overweight and more obese than those born in foreign countries [5]. As the largest subgroup of Asian American, Chinese Americans have increased rates for obesity and the rates of obesity increased with years of residence [5,6]. Limited studies have been conducted regarding obesity assessment and management in Chinese Americans.

The anthropometric measures of body mass index (BMI) are traditional measures for obesity [7]. However, research suggests established cut-points for classifying obesity with BMI may not apply to Asian and Asian Americans [8]. Obesity related health problems such as diabetes, hypertension, cardiovascular diseases have been identified at lower BMI for Asian and Asian American population [9]. Though multiple studies have conducted to examine and compare general obesity indicator including BMI, weight, body fat percentage with central obesity indicators including waist circumference [WC], hip circumference [HC], weight to
 height ratio, the results are mixed. Little is known about obesity indicators in Chinese American. 
Though obesity is a potential and major risk factor for many chronic health problems including diabetes, hypertension, stroke, cardiovascular diseases and certain types ofcancer, substantial uncertainty remains, however, about which measures of obesity indicator more strongly predict hypertension, diabetes, heart diseases, and whether the association between obesity and chronic illness are due to obesity or due to the joint effects of obesity together with other factors. The purpose of this study therefore was to examine obesity indicators and chronic illness, and the relationship between them among Chinese Americans.
 

Study design

Setting and sample

Data collection procedure

Measurements

Data analysis

Demographic characteristics of subjects

Multiple chronic illnesses

Obesity indicators and numbers of chronic illnesses

Obesity indicators and common chronic illness

As a pilot study, the results of this study added to the literature by examining the relationship between chronic illness and obesity indicators in Chinese Americans for the first time. In this study, 148 subjects (91.2%) had chronic illness. This study might over-present non-healthy Chinese Americans in the United States. The average age of this population was 58 and the majority of the subjects have been immigrated into USA for more than 20 years. This population in this study therefore represents old Chinese Americans who have immigrated to the United States for a relatively long period of time, and cannot represent the younger Chinese Americans and new Chinese immigrants in the United States.

The majority of the subjects in this study had diabetes (65%), and around half of the population had hypertension (46.7%). In a survey of 2,071 Chinese Americans living in the New York City, more than 38% of subjects were reported to have diabetes [11]. Another study reported that among 125 subjects recruited from health fairs in New York City, 13% of Chinese Americans had hypertension. The percentages of diabetes and hypertension in our study were higher that what were in the literature. Possible reason could be that many subjects in this study were recruited from a community center specialized in diabetes care, therefore many patients with diabetes and/or hypertension were recruited. Another reason could be that old age and longer immigration time in this population increased the risk for obesity-related chronic illness.

Many obesity indicators in this study had significant associations with number of chronic illnesses. Patients with increasing WC, HC, BMI, weight to height ratio were more likely to have more multiple chronic illnesses. Obesity has been reported to be a significant risk factor for morbidity and mortality of many health problems [12,13]. While some studies found that there were larger associations between hypertension and diabetes with BMI in Chinese Americans, compared with American Whites and Blacks [14,15], other studies reported that central adiposity, such as increased WC and HC, weight to height ratio were reported to be more sensitive obesity indicators to screen diabetes or other chronic illnesses, compared with BMI or general adiposity indicators [16]. In Chinese Americans, measuring both general and central adiposity to classify and quantify obesity and obesity-related risks are necessary [12]. Our study showed that WC, HC and weight to height ratio remained to be significant predictors for increased numbers of chronic illnesses, which BMI was unable to achieve significant prediction, after controlling other significant factors such as age (P<0.001), marital status (P<0.001). This finding was consistent with the part of the literature that measurement of central obesity indicators was more sensitive obesity indicators for Asian Americans [17]. Another similar study found that WC alone was a significant predictor for obesity related health risks, but not BMI, among 924 adult participants in the third National Health and Nutrition Examination Survey [18].

Increased BMI, WC, HC, HbA1C, FBS were not only associated with the numbers of chronic illnesses, but also with individual chronic illness such as diabetes, hypertension, heart disease, eye problems in this study. Previous studies have reported that overweight and obese subjects were more likely to have hypertension than normal-weight subjects [15,18]. Obesity was associated with increased risk of sudden cardiac death in middle-aged, non-smoking individuals, mediated by traditional cardiovascular risk factors [19]. The associations between HbA1C and eye and food problems were also consistent with the literature. For diabetic patients, HbA1C and duration of diabetes have been reported to be associated with cataract [20]. For every 2% elevation of glycated hemoglobin (HbA1C), the risk for diabetic retinopathy increased by a factor of 1.7 (95% CI: 1.545-1.980; P<0.0001) [21]. HbA1C was found to be an important biomarker in predicting wound healing rate in diabetic patients [22]. The strong association between HbA1C and hypertension, eye problem and food problem supported that HbA1C, as a measure of long-term glycemic control, was the best surrogate indicator of diabetes related mortality and morbidity. Obesity indicators were not associated with skin problems in our study. Given minimal studies have been conducted regarding obesity and skin problems, further study are needed to verify the results.
 

There are several limitations in the study. First, the sample size of this pilot study (162 participants) was small compared to epidemiological surveys. Given Chinese American population was a minority population and usually very small sample size could be identified in national surveys in the United States, the findings of this study should be able to help understanding obesity and chronic illnesses in this population. Second, most of subjects had at least one chronic illness and non-healthy Chinese Americans might be over-presented in this study. Third, we did not examine some blood biochemical indicators related to obesity such as cholesterol, liver function and thyroid function in this study, which was reported to be related to obesity related chronic illnesses in the literature, future research studies should include these variables among Chinese Americans.
 

As the first study to examine the relationship between obesity indicators and chronic illnesses among Chinese Americans, the study identified both general obesity (BMI) and central obesity indicators (WC HC, and weight to height ratio) were associated with increased numbers of chronic illnesses, controlling for other demographic factors. The study also found that HbA1C had strong relationship with multiple chronic illnesses including diabetes, hypertension, heart diseases, and eye and foot problems. This study is a pilot study and future studies with larger sample size are needed to verify the results of this study.
 

This research was supported by a research grant awarded by NYU Pless Center of Nursing Research, Association of Chinese American Physicians, and the National Institute of Health (NIMHD Project # P60 MD000538-03). Its contents are solely the responsibility of the authors and do not necessarily represent the funders. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.